This study was initiated to understand the mechanism of re-differentiation of neoplastic cells by drugs and other chemical agents. The research is directed at present to determine: (1) the effect of dimethylsulfoxide (DMSO) and its analogs on the expression of Glutathione synthesis in hepatoma cell lines in culture and also transplantable hepatomas; (2) the effect of polar compounds such as DMSO, bisacetamides and antitumor agents on fetal expressions (such as alpha-feto-protein) in hepatomas and CEA in colon tumors; (3) the reversibility, when exposed to the above mentioned agents, of choriocarcinoma in tissue culture using HCG as marker; and (4) the role of the compounds mentioned above in redifferentiation of neuroblastoma cell lines.